A circuit emulation service relates to a clock synchronization technology. The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) 1.363.1 standard defines a synchronous residual time stamp (SRTS) method for implementing differential clock synchronization. In the SRTS method, a transmitter sends information about a frequency offset between a service clock and a common reference clock to a receiver using a residual time stamp (RTS) packet. The receiver performs clock recovery according to the frequency offset information in the received RTS packet.
However, when the receiver does not receive the RTS packet sent by the transmitter, an offset may occur on a phase, relative to a phase of a service clock signal of the transmitter, of a service clock signal generated by the receiver.